Electromagnetic contactor and means for damping the armature momentum



J. F. DRIES 3,339,160

ACTOR AND MEANS FOR DAMPING THE ARMATURE MOMENTUM 2 Sheets-Sheet l Aug. 29, 1967 ELECTROMAGNETIC CONT Filed Aug. 2, 1965 Aug. 29, 1967 J. F. DRIES 3,339,160 ELECTROMAGNETIC CONTACTOR AND MEANS FOR DAMPl NG THE ARMATURE MOMENTUM 'Filed Aug. 1965 2 Sheets-Sheet 2 8 /6 56 6 4 'IlIl ln l" 3 1 f n f. 25"

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United States Patent C) 3,339,160 ELECTROMAGNETIC CONTACTOR AND MEANS FOR DAMPING THE ARMATURE MOMENTUM Jerome F. Dries, Hales Corners, Wis., assignor to Cutler- Hammer, Inc., Milwaukee, Wis., a corporation of Delaware Filed Aug. 2, 1965, Ser. No. 476,234 12 Claims. (Cl. 335-124) ABSTRACT F THE DISCLOSURE A reversing contactor having a pivotable, symmetrical v armature carrying bifurcated bridging contacts. Nylon This invention relates to electromagnetic contactors, and more particularly to those contactors which may be used as reversers or transfer switches.

It is a primary object of this invention to provide a contactor of the aforementioned type which is of the double pole, double throw type with a center-off position.

It is a further object of this invention to provide a contactor of the aforementioned type which is capable of handling high current ratings but is compact and simple in design.

It is still another object of this invention to provide a contactor of the 'aforementioned type which will rapidly move from one operated position to a center-off position without traveling past that position to the other operated position.

These and other objects will become more apparent in the following specification and. claims when read in conjunction with the drawings; wherein:

FIGURE lis a side elevational view of a reversing contactor with an electrical interlock assembly mounted thereon;

FIG. 2 is a front elevational view of the contactor of FIG. 1 with the electrical interlock assembly removed;

FIG. 3 is a cross-sectional view taken on line 3-3 of FIG. 1;

FIG. 4 is a cross-sectional View taken on line 4-4 of FIG. 2;

FIG. 5 is a fragmentary view of a contact assembly incorporated in the contactor of FIG. 1;

FIG. 6 is a fragmentary sectional view taken on line 6 6 of FIG. 5;

FIG. 7 is a top plan view of the contacts and a biasing member of FIGS. 5 and 6;

FIG. 8 is a fragmentary sectional view of a centering mechanism incorporated in the contactor of FIG. 1;

FIG. 9 is a fragmentary View showing a blow-out structure which may be incorporated in the contractor of FIG. l; and

FIG. 10 is a sectional view taken on line 10-10 of FIG. 9.

The contactor comprises an insulating base 2 which has stepped-down surfaces extending along two opposite edges. A plurality of main stationary contact posts 4 are secured to the base 2 on the stepped-down surfaces by bolts 6 so that one side of the post abuts the ridge formed by the different surface levels of the base to maintain the posts in alined relation. The contact posts 4 are all identical, each being square in cross-section, and having silver alloy or the like contacts secured to their outer ends and a pair of tapped holes (not shown) formed transversely of their longitudinal dimension. A plurality of bolts 8 are provided which take into the tapped holes formed in the posts 4 to secure cross-connector bars 10 and 12 and connector plates 14 and 16 to their respective posts. The bolts 8 are of suflicient length to also secure wiring lugs to the posts, or as in the case of plates 14 and 16, the lugs may be secured by bolts and nuts utilizing the pair of holes provided in the central area of the plate.

A T-shaped magnet frame 18 is secured to the base 2 by a pair of bolts 20 which are inserted from the rear of the base into counterbored clearance openings in the base and pass through alined clearance openings in the frame to take into threaded holes in coil cores 22 as is best shown in FIG. 4. Each core has an electromagnetic energizing coil 24 mounted thereon in a conventional manner.

With further reference to FIG. 4, it may be seen that a mounting strap 26 is mounted to the base 2 by a pair of bolts 28 which take into threaded holes in the back of the base. A thin insulating strip 30 is placed between the strap 26 and the base 2 to cover the heads of bolts 20 to insulate strap 26 from the frame 18.

A T-shaped armature 32 is secured to an outwardly extending leg 18a of frame 18 by a pivot pin 34. To assist in maintaining the pivot pin 34 centered in position, a spring biased key 36 is provided in the leg 18a. Key 36 is a round-headed shouldered pin biased inward by a leaf spring 38 as seen in FIG. 4. Pivot pin 34 has an annular groove 40 located midway between its ends into which the rounded head of key 36 tits to hold the pin 34 in lateral position. A screw 42 takes into a threaded hole in the end of the leg 18a which opens into the hole for pin 34 at right angles thereto. By threading the screw 42 tight against the pin 34 the latter is securely held in position.

AS previously mentioned, the armature 32 is T-shaped and a central opening 44 is provided which extends through the top leg of the T and down along the upstanding base leg to divide that leg into two separate legs 32a and 32b which straddle the outwardly extending leg 18a of frame 18. Each end of the top leg of armature 32 has a machined pad 46 which seats against the outer surface of the end of the respective core 22 when the re.- spective coil 24 is energized. An insulating contact block member 48 is secured to each end of the top leg of the armature on the side opposite the pad 46 by a bolt 50 and countersunk screw 52. A U-shaped sheet 54 of insulating material is interposed between the armature and each contact block.

Each contact block 48 has a contact mounting member 56 riveted to each end as seen best in FIGS. 2 and 5. The Iblock 48 has a raised portion on its underside at each end and the members 56 are riveted in this area. The insulator 54 serves to insulate the armature 32 from the members 56. Each contact mounting member 56 has a Ipair of contacts 58 mounted thereon. The contacts 58 are rectangular bars having a pair of contact pads secured one at each end and have a threaded post extending upward to pass through clearance holes in members 56. Self-locking nuts 60 are threaded to the posts of the contacts 58 to hold the latter to lthe member 56. An H- shaped leaf spring member 62, the proiile and shape of which is best seen in FIGS. 6 and 7, s placed between the upper surfaces of the contacts 58 and the under surface of member 56 to provide spring pressure to the contacts 58. While the contacts S8 are individual members and each relatively movable with respect to the member 56, the spring 62 is a common member to both contacts with each leg of the spring acting individually -upon its corresponding contact 58. Shims 64 may also be placed over the threaded posts of the contacts 58 between the H- 3 spring and member 56 to -provide prope-r contact adjustment, a pair of shims 64 being shown in FIGS. 5 and 6. Thus there is lprovided a bifurcated contact assembly at each end of the contact block 48 which bridge a pair of the main stationary contacts on posts 4 upon energization of one of the operating coils 24.

T-he armature 32 with its contact assemblies in place is essentially statically balanced about its pivot pin 34, this being accomplished by machining the ends of the divided center leg. Because of the symmetrical design of the armature, removal of the latter could result in the improper replacement of it with respect to top and bottom ends of the cross-leg and static balance. To prevent this a pin 66 (FIG. 3) is mounted in the outwardly extending leg 18a of the frame 18 which interferes with the ends of the legs 32a and 32h of the armature. One leg 32a is therefore provided with a relieved portion 68 to clear the pin 66 and thus the armature can only be replaced with that leg on the pin side of frame 18.

The contactor is also provided with an electrical interlock assembly which comprises a mounting plate 76 having four interlock switch assemblies 78 mounted thereon. Plate 76 has a central flat portion 80 offset from the con tour of the plate and of similar dimensions to the end of the outwardly extending leg 18a of frame 18. Flat portion 80 is provided with two clearance holes, one cen trally located to be in alinement with the scraw 42 and the other in line with a pin 82 mounted in the outer end of the leg 18a. The flat portion 80 and pin 82 prevent the mounting plate 76 from twisting out of a true position with respect to the contactor and also prevent the inten lock assembly from 4being replaced in a position other than its original position. The plate 76 is secured to the leg 18a by a nut 84 which is threaded onto screw 42. Each interlock switch assembly 78 has a plunger -86 extending through a plate 76 and biased toward the armature 32 by a spring biased contact carrier within the switch unit. Plungers 86 are -depressed by the contact blocks 48 upon movement of the armature to one or the other of its energized positions.

The divi-ded center legs 32a and 32h of armature 32 are also provided with an energy absorbing mechanism to absorb the unwanted energy that would tend to carry the armature overcenter upon its release from either one of its two possible sealed positions. A pin 70 of nylon or the like is placed in a clearance hole in each leg and is biased inward toward the leg 18a by a leaf spring 72 secured to the leg of the armature by a screw. The pin 70 has a shouldered head 74 at one end which cooperates with a slot in the free end of spring 72 to hold the pin to the spring Vwhile the other end is substantially at. The friction created between the flat end of the pins 70 sliding upon the smooth surface of the leg 18a during the pivotal movement of the armature 32 upon the release of an operated coil absorbs the angular momentum of the armature that would tend to carry it past its center position.

A pair of centering bias assemblies are also provided on the plate 76 to bias the armature to its center position depicted in FIG. 1. These assemblies each comprise a bolt 88 which passes through a clearance hole in the plate 76 and through a spacer sleeve 90 and has a sel-flocking nut 92 threaded onto the outer end. A helical compression spring 94 is disposed about the shank of the bolt 88 and bears against the head thereof and the plate 76, as best shown in FIG. 8, which is a fragmentary sectional view of the assembly. Bolts 88 are adjusted so that their headed ends are in close proximity with the heads of screws 52 in the contact blocks 48 so that when one end of the armature 32 is in its sealed position due to energization of the respective coil 24, the other end thereof will raise to cause the respective bolt 88 to compress ts spring 94. Upon deenergization of the coil, the compressed spring 94 will cause the armature to quickly return to its center position and the other bolt 88 and 4 spring 94 assembly, together with the energy absorbing pins 70, will cause the armature to stop at its center position.

In certain instances it is desi-rable to incorporate an arc blowout assembly in the contactor to direct any arc occurring upon contact separation away from an area whe-re it may cause damage to the contactor. A proposed means of achieving this is shown in FIGS. 9 and 10 wherein a magnetic blowout assembly is secured to one of the contact posts 4. The assembly comprises a U-shaped frame member 96 which is provided with a clearance hole in its bight portion and straddles the post 4 just behind the contact tip. A Irectangular piece 98 is secured to each leg of the frame member 96 by spot welding or the like, with the greater portion of the pole piece extending in the same direction as the leg to which it is secured and a lesser portion extending in the opposite direction as shown particularly in FIG. 10. A permanent magnet member 100 having a central clearance hole is placed on top of the bight portion of member 96 between the pole pieces and a screw 102 is placed through the clearance holes in the magnet 100 and frame 96 and t-hreaded into a tapped Ihole .formed in the post 4 to secure the assembly in place. The bight portion of frame 96 also has a portion 104 which extends outwardly of the Contact post 4 and is then formed upward past the magnet 100. The uppermost portion of extension 104 is bent back at a slight angle over magnet 100. The blowout assembly is mounted as described and shown in FIGS. 9 and 10 for the two contact posts 4 at the upper corners of the contactor, and is mounted on the bottom of the two posts 4 at the lower corners of the contactor. The arrangement of the ibifurcated bridging contacts 58 on the armature is such that the contact faces nearest the blowout magnet open slightly ahead of the faces closest to the armature pivot pin which causes the arc to `direct principally in the outer direction away -from the pivot pin even in the case of the bottom contacts.

Thus there is shown a reversing contactor which is capable of reliably handling high current ratings, yet is compact in design. The contactor may be readily disassembled for service and reassembled without danger of improper replacement of parts. By removing the crossconnector bars 10 and 12 the contactor may be used as a transfer switch.

While the contactor has been shown in a preferred embodiment it is capable of various modifications without departing from the scope of the appended claims.

I claim:

1. Au electromagnetic contactor comprising, in combination:

a base;

a frame member secured to said base;

electromagnetic means mounted on said frame includ ing armature means pivotable about a single axis to operated and neutral positions;

spring biased means to move said armature means to said neutral position upon deenergization of said electromagnetic means;

a plurality of sets of spaced pairs of stationary contacts mounted on said base;

a plurality of bridging contacts movable by said armature means to bridge respective sets of spaced pairs of stationary contacts upon energization of said electromagnetic means; and

damping means separate from said spring biased means and coacting between said armature means and said frame affording resilient, slidable engagement between said armature means and said frame to damp the momentum of saidl armature means when the latter is returned from an operated position to said neutral position by said spring biased means.

2. The combination according to claim 1, wherein said damping means comprises a member mounted to said armature means by spring means, said spring means biasing said member into abutting engagement with a substantially Hat, smooth surface of said frame through the travel of said armature means.

3. The combination according to claim 1, wherein said damping means comprises a pair of members mounted to said armature means by spring means, said spring means biasing said members into abutting engagement with substantially fiat, smooth surfaces of said frame in opposite directions throughout the travel of said armature means.

4. An electromagnetic contactor comprising, in combination:

a base;

a frame member secured to said base;

a pair of spa-ced electromagnets mounted on said frame;

a symmetrical armature pivotally mounted about a single axis on said frame between said electromagnets for movement into engagement with one or the other of the latter according to their energizations;

spring biased centering means acting upon deenergization of either electromagnet to eiect return of said armature to a center-01T position;

a plurality of sets of spaced pairs of stationary contacts mounted on said base;

a plurality of bridging contact assemblies carried by said armature to bridge respective sets of spaced pairs of stationary contacts upon energization of one or the other of said electromagnets; and

damping means separate from said centering means carried by said armature affording resilient, slidable engagement with said frame to damp the angular momentum of said armature when the latter is returned from an operated position to said center-off position by said centering means.

5. The combination according to claim 4, wherein said armature is generally T-shaped and having a central opening in its top leg, and spaced base legs disposed on opposite sides of said opening, said armature being mounted to said frame so that said frame protrudes through said opening and said spaced base legs straddle said frame.

6. The combination according to claim 5, together with a pivot pin for mounting said armature to said frame at a point substantially located at the junction of the spaced base legs and the top leg of the armature, said pin passing through each of said spaced base legs andv through an opening in said frame, and having a centrally located annular groove, and a pin mounted on said frame, spring biased to extend transversely into said opening for said pivot pin to engage said annular groove in said pivot pin.

7. The combination according to claim 6, together with an auxiliary switch assembly mounted on said protruding portion of said frame, and means to secure said auxiliary switch assembly to said protruding portion, said means also engaging said pivot pin within said frame to additionally secure said pivot pin in position.

8. The combination according to claim 4, wherein said damping means comprises a member mounted within a clearance opening in said armature by spring means carried by said armature, said spring means biasing said member into abutting engagement with a substantially flat, smooth surface of said frame throughout the travel of said armature.

9. The combination according to claim S, wherein said damping means comprises a pair of members, one of said members mounted within a clearance opening in each of said spaced base legs by spring means carried by each of said base legs, said spring mean biasing said members into abutting engagement with a substantially flat, smooth surface of said frame throughout the travel of said armature, and said members being axially opposed to act upon said frame in opposite directions.

10. The combination according to claim 5, wherein said bridging contact assemblies are mounted at each end of an insulating contact board, a contact board being transversely mounted at each end of the top leg of said armature, said bridging contact assemblies each comprising a support member mounted to and extending from said contact board and having a pair of spaced clearance openings therein, a pair of individual contact members each having a member extending outwardly thereof to pass through said clearance openings in said support member, an H-shaped spring member having a pair of clearance openings in alinement with said openings in said support member, said spring member being disposed between said support member and said contacts so that the legs of the spring lie one along each contact to alford individual bias to each contact, and means disposed at the outer ends of said outwardly extending members of said contact to hold said contacts to said support member.

11. The combination according to claim 7, wherein said centering means comprises a pair of members which extend through clearance holes in said auxiliary switch assembly and are spring biased outwardly of said assembly toward said armature, said members having a threaded end and a nut disposed thereon to adjust the distance said member extends toward said armature, and wherein said members are adjusted so that they extend to points in close proximity to each end of said armature when the latter is in said center-olf position.

12. The combination according to claim 4, together with individual blowout means provided for each set of spaced pairs of stationary contacts to be bridged, said blowout means comprising a U-shaped frame member having pole pieces secured to and extending along the legs of said U-shaped frame member, a permanent magnet on said frame' member between said pole pieces, means for securing said permanent magnet and said frame member upon one contact of said set of stationary Contact members so that said pole pieces extend along the contact toward the other contact of said set, and an extension of said frame member extending rst outwardly in the direction of the contact faces and then in a direction away from said set of stationary contacts.

References Cited UNITED STATES PATENTS 2,564,246 8/1951 Bourne 335-181 BERNARD A. GILHEANY, Primary Examiner. R. N. ENVALL, JR., Assistant Examiner. 

1. AN ELECTROMAGNETIC CONTACTOR COMPRISING, IN COMBINATION: A BASE; A FRAME MEMBER SECURED TO SAID BASE; ELECTROMAGNETIC MEANS MOUNTED ON SAID FRAME INCLUDING ARMATURE MEANS PIVOTABLE ABOUT A SINGLE AXIS TO OPERATED AND NEUTRAL POSITIONS; SPRING BIASED MEANS TO MOVE SAID ARMATURE MEANS TO SAID NEUTRAL POSITION UPON DEENERGIZATION OF SAID ELECTROMAGNETIC MEANS; A PLURALITY OF SETS OF SPACED PAIRS OF STATIONARY CONTACTS MOUNTED ON SAID BASE; A PLURALITY OF BRIDGING CONTACTS MOVABLE BY SAID ARMATURE MEANS TO BRIDGE RESPECTIVE SETS OF SPACED PAIRS OF STATIONARY CONTACTS UPON ENERGIZATION OF SAID ELECTROMAGNETIC MEANS; AND DAMPING MEANS SEPARATE FROM SAID SPRING BIASED MEANS AND COACTING BETWEEN SAID ARMATURE MEANS AND SAID FRAME AFFORDING RESILIENT, SLIDABLE ENGAGEMENT BETWEEN SAID ARMATURE MEANS AND SAID FRAME TO DAMP THE MOMENTUM OF SAID ARMATURE MEANS WHEN THE LATTER IS RETURNED FROM AN OPERATED POSITION TO SAID NEUTRAL POSITION BY SAID SPRING BIASED MEANS. 